Casing for preparation of dry sausages



Dec. 25, 1967 H.J. ROSE ETAL 3,360,383

CASING FOR PREPARATION OF DRY SAUSAGES Filed Sept. 8, 1 964 mmvroa FEW/7J, R086? fl/bm K7T/rbak r0 DRYER v United States Patent Illinois FiledSept. 8, 1964, Ser. No. 394,817 7 Claims. (Cl. 99-176) ABSTRACT OF THEDISCLOSURE A casing for the preparation of dry sausages is prepared bycoating the inner surface of a synthetic tubular casing with a solubleprotein which is insolubilized by liquid smoke. The protein has amolecular weight above about 10,000 and is added in a solutioncontaining 0.1- 5.0% soluble protein and sufiicient liquid smoke in therange of about ODS-5.0% by weight of the casing being treated tosubstantially insolubilize the protein coating after drying. Thetreatment is preferably given to regenerated cellulose casings andespecially to fiber reinforced regenerated cellulose casings. Thetreated casing with the insolubilized proteinaceous coating adheres tothe surface and shrinks with the dry sausages which are processed in thecasing.

This invention relates to new and useful improvements in sausagecasings, and more particularly to improvements in casings used in themanufacture of dry sausages.

Dry sausage, of which the various salami and cervelats are primeexamples, is conventionally processed by drying rather than by cooking,hence the name. Dry sausage is ordinarily served cold, without furthercooking by the housewife.

The manufacture of dry sausage customarily involves mixing desiredproportions of fat and lean meats, beef or pork, with selected spices,seasonings and curing materials to form an emulsion which is initiallycured at a few degrees above freezing (36 to 38 F.), for two or threedays depending upon the size of the meat particles so that they will bepreserved sufficiently to be smoked and dried.

The chill cured meat emulsion is then firmly packed into casings ofsuitable size and shape, and the ends of the casing are tied ready fordelivery to the drying room or smokehouse, dependent upon the type ofsausage. The smoked dry sausage is smoked and then dried, while unsmokeddry sausage is dried only. The drying or curing time will vary with theparticular type of sausage being processed and to some extent with theprocessing conditions. However, 60 to 90 days is usually considered aminimum time and periods of 120 to 180 days or more are used under somecircumstances.

The processing of dry sausage is described fully in Sausage andReady-to-Serve Meats, published by the American Meat Institute. The termdry sausage as used herein includes the entire range of dry and semi-drysausages. The semi-dry sausages include the thuringer cervelats whichare dried for about days (other semi-dry sausages may be dried as shorta time as 2 to 6 days). Dry sausage is usually sold in three differentforms; first, new sausage or semi-dry sausage, about 10 to 25 days aftersmoking (having about 20% shrinkage); second, medium dry sausage, about30 to 60 days after smoking (having about 32% shrinkage); and drysausage, about 60 to 90 days or more after smoking (having about 40%shrinkage).

Previously, the sausage meat emulsions were stuffed into casings formedof natural materials or animal products such as sewn beef middles andhog casings. More ice recently, considerable interest has been developedin utilizing certain synthetic materials out of which casings could beformed. Particularly, the industry has turned to the use of casingsformed of regenerated cellulose per se or of the product known in theart as fibrous casing and which is composed of cellulosic fibersimpregnated and held together by regenerated cellulose.

The use of such synthetic materials is not only desirable because of thegreater control over the supply that can be exercised in keeping withthe rapid growth and demand of the various packaged and/or cased meatproducts, but also the materials can be conventionally synchronized andextruded into seamless tubular form of preselected diameter. Mostimportantly, casings formed of the aforesaid fibrous materials, unlikethe natural product can be made sufficiently flexible as well as durableto be advantageously used in the stuffing step, while also beingsufficiently nonelastic that they will not stretch out of shape duringor subsequent to stufiing, but will retain a more constant shape andsize corresponding to that to which it was initially fabricated.

This, of course, permits a definite relation to be established betweenthe number of slices of the sausage and weight which may be assembled asa unit, and is obviously a highly desirable characteristic in themechanical high speed packaging methods employed today. In addition, thecellulosic casings are much more sanitary than natural casings, and aremore economical to use where they do not require tying with strings tomaintain their shape.

However, one of the essential drawbacks of such cellulosic materials istheir lack of ability to shrink with the sausage during the drying ofthe sausage emulsion. In the preparation of dry sausages, the sausagetends to shrink away from the cellulosic casing and leave gaps betweenthe meat and the casing in which there is a tendency for mold and/or socalled brown ring to develop. This trouble is not encountered wherenatural casings are used since natural casings tend to expand andcontract with the sausage during curing.

It is, therefore, one object of this invention to provide an improvedcellulose casing which adheres to a dry sausage emulsion and follows theshrinkage of the sausage during curing.

A further object of this invention is to provide a method of treating asausage casing to cause the same to ad-. here to the sausage and followthe shrinkage thereof during curing.

Still another object of this invention is to provide a method of coatingcasings of regenerated cellulose materials to cause the same to adhereto meat encased therein, and to follow the shrinkage of the meat duringcuring.

Yet another object of this invention is to provide an improved coatingcomposition for application to regenerated cellulose casings.

A feature of this invention is the provision of a regenerated cellulosecasing of tubular shape or a blank for formation of a regeneratedcellulose casing of tubular shape having the inner surface thereofcoated with a protein, such as gelatin, and a liquid smoke which iseffective to insolubilize the protein coating after drying, whereby thecasing shrinks with and adheres to the surface of dried sausage therein.

Another feature of this invention is the provision of a process formanufacture of sausages in which a cellulosic casing is coated, prior tostufiing with the meat, with a solution of a protein, such as gelatin,and liquid smoke and then dried to insolubilize the protein coating,which causes the casing to adhere to and shrink with the meat duringdrying and to eliminate substantially the problem of brown ringformation in the resulting sausage, I

Another feature of this invention is the provision of a casing for drysausage preparation having an internal coating of a water soluble filmformer which will not dissolve or disperse during filling with meatemulsion.

Still another feature of this invention is the provision of an improvedcoating composition comprising a solution of gelatin and liquid smoke.

Other objects and features of this invention will become apparent fromtime to time throughout the specification and claims as hereinafterrelated.

SUMMARY OF THE INVENTION In recent years, regenerated cellulose casings,both fibrous and nonfibrous types, have been made and sold commerciallyfor use in the manufacture of dry sausages. These casings have beencoated on their inner surfaces with a thin layer of gelatin which iseffective in causing the casing to adhere to a dry sausage emulsion andfollow the shrinkage of the sausage during curing. Gelatin coatedregenerated cellulose casings of this type, however, are subject to thedisadvantage that they must be soaked in water prior to use and thissoaking generally results in a very substantial loss of the gelatincoating. As a result there has been a substantial failure of adhesion ofcasings to dry sausages during processing which has resulted in theproduction of unsatisfactory sausage products. The loss of gelatinduring the soaking step can be offset to some extent by application of aheavier gelatin coating. The thickness of the gelatin coating however,is determined largely by the concentration of gelatin in the solutionused to coat the casing and the coatings which have been usedcommercially are at a maximum practical thickness.

This invention is based upon our discovery that regenerated cellulosecasings, including regenerated cellulose films, paper reinforcedcellulose casings, both in flat form and in tubular form, can be treatedwith a mixture of a soluble protein, such as gelatin, and a liquidsmoke, in solution, to produce a coating thereon which is effective incausing the casing to adhere to coat dry sausage emulsion and follow theshrinkage of the sausage during curing. During the heating and drying ofthe casing after being coated with the solution of protein and liquidsmoke, the protein is substantially insolubilized by reaction with someof the ingredients in the liquid smoke. As a result, a much smalleramount of the protein is lost during presoaking of the casing with theresult that the .coated casings are 'almost totally effective inadhering to dry sausages during curing.

Where the protein used is gelatin, the incorporation of liquid smokeinto the coating composition also provides certain additional advantagesin the preparation of the casing. It has been found that theincorporation of liquid smoke into gelatin solutions renders suchsolutions more fiuid and less likely to gel for extended periods oftime. This enables one to coat the interior of casings, as issubsequently described, over an extended period of time without dangerof gelation of the coating solution. It has also been found that theincorporation of substantial amounts of liquid smoke into a gelatincoating is effective to prevent brown ring formation which occursoccasionally in the preparation of dry sausages.

In carrying out this invention we may use any of the soluble proteinshaving molecular weights above 10,000 and an isoelectric point in therange from about pH 2 to pH 6. These soluble proteins include (but arenot limited to) the albumins, globulins, glutelins, prolamines,prolines, hydroxyprolines, histones, elastins, and protamines. Typicalexamples are egg albumin, edestin, glutenin, procollagen, gelatin,gliadin, etc.

Liquid smoke as used in this invention is an aqueous solution of theessential soluble components of wood smoke which is obtained by washinga wood smoke or' by fractionating a wood smoke and absorbing thenontoxic flavoring ingredients into an aqueous solution. The

liquid smoke is prepared by burning a suitable wood, preferably maple orhickory, sawdust on a hot plate in a limited amount of air. The smoke isdrawn through a settling chamber where ash and heavy tars fall out andis then dissolved in water. The smoke solution is further processed byfiltration and attains a concentration of approximately 48% acetic acid.The solution has a phenolic content (dimethoxyphenol) of about 40-80mg./ml., and a pH of about 2.15. The liquid smoke consists of a solutionin water or other suitable solvent of substantially all of the coloringand flavoring ingredients of natural wood smoke with only the ash, heavytars, and other particulate matter removed.

Liquid smoke has been approved for use in foods by the United StatesFood and Drug Administration, and by the Meat Inspection Division of theUnited States Department of Agriculture.

In coating tubular cellulose sausage casings, both unreinforced andfibrous types, an aqueous solution is used containing 0.1-5% solubleprotein, such as gelatin and ODS-5.0% liquid smoke. The concentration ofsmoke ingredients is expressed on a percentage basis based on the amountof smoke ingredients in the solutions which are applied onto the casingby addition of the specified percentage of the liquid smoke as anaqueous solution.

It has also been found that the incorporation of a small amount, e.g.0.05-l.0%, of an insoluble non-toxic powder, in the coating solutionwill result in the powder being fixed in the resulting coating andfunctioning as an antiblocking agent for the internal surface of thecasing. Powdered materials which may be used in the coating compositioninclude wood flour, starch, walnut shell flour, chalk, talc, powderedmica, graphite, calcium phosphate, calcium carbonate, etc.

In carrying out this invention, the aqueous solution containing 0.15%soluble protein, such as gelatin, and 0.05-5% liquid smoke is applied tothe ultimate meat contacting surface of the casing (or sheet materialfrom which the casing is to be formed) so that an amount in the rangefrom about 0.1-5% 0f the protein and 0.05- 5% of the liquid smoke iscoated on the casing. As noted above, the coating composition mayinclude 0.051.0% of walnut shell flour or starch as an anti-blockingagent. The coating can be applied to the casing in any desired way.Thus, application to conventional regenerated cellulose casing, fibrouscasing, or any other kind of casing can be made by coating the insidesurfaces of the tubular casing by a technique which involves the use ofa bubble of aqueous solution, emulsion, or suspension of the coatingingredients inside the tube. In this method of coating, the casing moveswhile the bubble of liquid remains still, with the result that the innersurface of the casing is wetted and coated and then moves on beyond thebubble to a casing dryer. During the drying step the liquid smoke reactswith the protein to insolubilize it without detracting from theproperties of promoting adhesion to the surface of dry sausage whenprocessed in the casing.

The coating technique is better illustrated in the following descriptionof the bubble coating method as applied to a commercial production lineof either regenerated cellulose tubing or casing or paper reinforcedcellulose casing which is known in the trade as fibrous casing.

In the accompanying drawing, to be taken as a part of this specificationthere is clearly and fully illustrated a preferred embodiment of thisinvention, in which draw- FIG. 1 is a diagrammatic view illustrating theformation of an interior coating in sausage casing prior to itsintroduction to a dryer.

BUBBLE COATING PROCEDURE Referring to FIG. 1 of the drawing, casingwhich may be wet fibrous casing or wet unreinforced regeneratedcellulose casing 1 in a collapsed flat form is transferred from a bath(not shown) in which the casin has been washed after being impregnatedwith viscose followed by regeneration, or in the case of regeneratedcellulose casing, after regeneration (both of these being well knownprocesses for the preparation of fibrous or regenerated cellulosecasing), into a slack box 3, by passage over rolls 2. Between the rolls2 and slack box 3, an aqueos solution containing 2% gelatin (or othersoluble protein) and 2% liquid smoke (either Solu-smoke or Charsolbrands may be used), is placed within the casing 1, the solution beingadmitted through out 5 in the casing 1 before rubber couplers 6 are tiedinto casing 1.

The solution can be made by mixing gelatin with cold tap water andallowing the gelatin to swell for about one half hour. To this mixturethere is added hot tap water with agitation and heating to 50 C. for aperiod of 5 min. There is then added an amount of liquid smoke solutionequal to the weight of gelatin used. The batch is stirred and maintainedat 4550 C. This solution is stable against gelling for periods of up to16 hours. If desired, up to 20% glycerol may be included in the solutionto assist in plasticizing the casing and the film which is formed as acoating on the inside of the casing.

A preferred coating composition consists of tap water containing 2%gelatin and 2% liquid smoke and may optionally include up to 20%glycerol. The liquid smoke performs several functions in the coatingcomposition. Liquid smoke is etfective to maintain the gelating solutionfluid and resistant to gelling for extended periods of time (e.g. up to16 hours or more). It is also etfective, after drying, to fix thegelatin coating on the casing and to render it substantially insolubleto prevent appreciable loss of gelatin during presoaking of the casingjust prior to use.

The bubble 4 of the coating solution lies at the bottom of slack box 3,and as casing 1 moves as shown, the interior of casing 1 isprogressively contacted with bubble 4, and is forced open to conform tothe configuration of the bubble. The bubble is refilled with additionalsolution as it becomes depleted, preferably at intervals of one or twohours.

Casing 1 then passes over additional rollers7 which are subjected to adrying atmosphere, air being maintained within casing 1, as shown, forsize control. Casing 1 then passes through idler roll 8 and roll wheel 9into dryer 11 (not shown) where it is further dried at a temperature ofabout 200 F. for a period of 5 to 15 min. In this last drying step, thecoating ingredients become firmly attached to the inner surface of thecasing and the gelatin is insolubilized as previously described.

This procedure is effective to apply a coating of 0.1-5 gelatin (basedon weight of the casing) and smoke ingredients corresponding to 0.05-5%liquid smoke, inside the casing.

The drying time and temperature are interdependent factors insofar asaffecting the drying of the casing and the nature of the resulting filmare concerned, as will be apparent to those skilled in the art. Othercombinations of time and temperature besides those illustrated above,can be used, provided of course, that the temperature is not so high andtime not so long that the casing itself or the coating film is injured.

When other soluble proteins are used in the coating solution dryingtimes and temperatures are selected which are appropriate for theparticular protein. For best results, temperatures of about 175 to 225F. or higher should be used.

Under the above described conditions, a number of runs were made, usingfibrous casing as the casing being treated, as follows:

Example I Various casings were coated on the inside and dried using theabove described application technique, the coating being accomplishedusing a solution containing 2% gelatin, 2% liquid smoke (eitherSolu-smoke or Charsol brand), and 0.2% cornstarch. The coated casingswere easy to open as a result of the anti-blocking action of starchparticles in the coating.

The casings were presoaked in hot water according to standard commercialpractice and were stuffed with salami emulsion. The stuffed casings werecured over a period of 6-8 weeks at a temperature of 50 F. and relativehumidity of 70%. Over this extended period of time there was a verysubstantial shrinkage of the sausage as the sausage emulsion was cured,and in each case the casing adhered to and followed the shrinkage of thesausage so that there was no separation of the casing from the sausage.The casings which contained both gelatin and liquid smoke in the coatingwere found to strip from the sausage with the normal tendency to pullaway meat.

In several months of commercial use of fibrous casing prepared and usedin this manner, it has been found that the casings adhere to and followthe shrinkage of the sausage during curing while untreated casings arelargely ineffective and subject to the objections previously discussed.Casings prepared in this manner were found to be unexpectedly improvedin appearance. Stuffed sausages were found to have a much higher glosswhich may be related to improved adhesion. It has also been found thatcasings which are prepared as described above, incorporating bothgelatin and liquid smoke in the coating, lose only a very smallproportion of the gelatin coating, e.g. about 10%, while casings whichhave been coated with gelatin alone can lose up to 95% of the coatingduring the presoaking period.

Example 11 A coating solution is prepared by mixing 2% egg albumin and2% liquid smoke into cold tap water. If desired, up to 20% glycerol maybe included in the solution to assist in plasticizing the casing and thecoating, and 0.05-1.0% wood flour may be included to provide anon-blocking coating.

This coating solution is applied to regenerated cellulose casing (eitherfibrous or non-fibrous type) by the bubble coating procedure describedabove. This procedure is eflfective to apply a coating of 0.1-5% albuminand 0.05-5% of liquid smoke inside the casing. After drying, the coatingis substantially insoluble in water and adherent to dry sausage duringprocessing.

Example III A coating solution is prepared by mixing 2% glutenin and 2%liquid smoke into cold tap Water. If desired, up to 20% glycerol may beincluded in the solution to assist in plasticizing the casing and thecoating.

This coating solution is applied to regenerated cellulose casing (eitherfibrous or non-fibrous type) by the bubble coating procedure describedabove. This procedure is effective to apply a coating of 0.1-5% gluteninand 0.055% of liquid smoke inside the casing. After drying, the coatingis substantially insoluble in water and adherent to dry sausage duringprocessing.

Besides the foregoing techniques for applying coating of gelatin andliquid smoke to the inside surfaces of casing, such coatings can also beapplied to the surface or surfaces or cellulosic sheets per se "beforethey are formed into tubes. For example, sheets of cellulose impregnatedfibrous sheeting can be treated in accordance with the present inventionby applying to the surface thereof, a coating of gelatin and liquidsmoke from solution, suspension, or emulsion, in an amount suflicient touniformly coat the surface with 0.1-5% gelatin and 0.055% liquid smoke.

After drying, the gelatin is substantially insolubilized. After thistreatment, the sheeting can be formed into a tube by any conventionaltechnique. Additional coating may be applied to the sheet after it hasbeen impregnated with cellulose and the coating may be applied to thesheet material in a bath through which the sheet passes prior to beingdried. The coating can also be applied to the sheet after it has beenwashed and dried.

It is seen from the above description that the technique of thisinvention results in the production of highly and unexpectedly superiorfibrous and regenerated cellulose casings with respect to theperformance characteristics of such casings when used in the preparationof dry sausages. The procedure is simple and lends itself to easyadaptation within the well known commercial fabrication of fibrouscasings and regenerated cellulose casings and involves the use ofextremely small amounts of materials Which are easy to apply andeffective for the purposes of the invention.

The coatings which are applied within the casing do not adversely affectthe desirable permeability characteristics of the casing with respect tomoisture vapor, smoke, dyeing, and the like.

As described above, the coating of gelatin and liquid smoke is effectiveto cause the casing to adhere to dry sausage during curing and to causethe casing to shrink with the sausage during the curing process.

While this invention has been described with special emphasis upon thetreatment of ordinary regenerated cellulose and fibrous casing, it willbe seen that it is also applicable to coating the inside surfaces ofcasings whose outside surfaces are coated with saran or other polymercompositions, such as the casing described in US. Patents 2,812,259,2,627,471, 2,627,483, and the like, as well as casing made from othersuitable casing films, e.g. a-lginates, amylose, polyvinyl alcohol,etc., both of the unreinforced and fibrous types.

While we have described our invention fully and completely with specialemphasis upon certain preferred embodiments, we Wish it to be understoodthat within the scope of the appended claims the invention may bepracticed otherwise than as specifically described herein.

What is claimed is:

1. A synthetic tubular sausage casing for processing dry sausages, saidcasing having the inner surface thereof coated with 0.1-% solubleprotein, having a molecular weight above about 10,000 and an isoelectricpoint in the 8 range from pH 2 to pH 6, and sufiicient liquid smoke inthe range from about ODS-5.0% by weight of the casing, to substantiallyinsolubilize the protein coating after drying, whereby the casingshrinks with and adheres to the surface of dry sausage therein.

2. A synthetic tubular sausage casing as defined in claim 1 in which thecasing material is regenerated cellulose.

3. A sausage casing as defined in claim 2 in which said soluble proteinis gelatin.

4. A sausage casing as defined in claim 3 in which the casing is of afiber-reinforced regenerated cellulose.

5. In the manufacture of dry sausage wherein sausage meat emulsion isstuffed into synthetic casings and stored for an extended time in anatmosphere of controlled temperature and humidity to dry the encasedmeat emulsion uniformly, the improvement which comprises coating theinterior of the casing, prior to stufling with meat, with 01-50% solubleprotein, having a molecular weight above about 10,000 and an isoelectricpoint in the range from pH 2 to pH 6, and 0.055.0% liquid smoke,sufiicient to substantially insolubilize the protein coating afterdrying, whereby the casing adheres to and shrinks with the meat duringdrying, and the finished sausage is substantially free from brown ringformation.

6. A process as defined in claim 5 in which the casing material isregenerated cellulose.

7. A process as defined in claim 6 in which said soluble protein isgelatin.

References Cited UNITED STATES PATENTS 3,106,473 10/ 1963 Hollenbeck99229 3,150,984 9/1964 Broadhead 99176 3,158,488 11/1964 Firth 99176 X3,170,797 2/1965 Sloan et a1 99109 FOREIGN PATENTS 589,274 6/ 1947 GreatBritain.

HYMAN LORD, Primary Examiner.

1. A SYNTHETIC TUBULAR SAUSAGE CASING FOR PROCESSING DRY SAUSAGES, SAIDCASING HAVING THE INNER SURFACE THEREOF COATED WITH 0.1%-5% SOLUBLEPROTEIN, HAVING A MOLECULAR WEIGHT ABOVE ABOUT 10,000 AND AN ISOLECTRICPOINT IN THE RANGE FROM PH 2 TO PH6, AND SUFFICIENT LIQUID SMOKE IN THERANGE FROM ABOUT 0.05-5.0% BY WEIGHT OF THE CASING, TO SUBSTANTIALLYINSOLUBILIZE THE PROTEIN COATING AFTER DRYING, WHEREBY THE CASINGSHRINKS WITH AND ADHERES TO THE SURFACE OF DRY SAUSAGE THEREIN.